"It was found over [the] last few years that each human racial group carried a Helicobacter that was relatively unique in that group." Professor Barry Marshall, a microbiologist at the University of Western Australia

A bacterial parasite known to cause stomach ulcers is shedding new light on ancient patterns of human migration across the Pacific region, according to an international study.

In the latest edition of Science, researchers report that their study of the distribution of Helicobacter pylori genotypes has given further weight to the theory that Australia was first populated around 30,000 years ago.

H. pylori is particularly useful for studying the movement of human populations because it is extremely widespread, and is transmitted from mother to child.

Co-author Professor Barry Marshall, a microbiologist at the University of Western Australia, says H. pylori is a lot like mitochondrial DNA, which is also used to investigate human migration patterns.

“You catch [H. pylori] off your mother,” says Marshall. “All of us carry our mothers’ mitochondrial DNA and that goes all the way back through the generations.”